﻿// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
// without restriction, including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Threading;

using ICSharpCode.AvalonEdit.Rendering;
using ICSharpCode.AvalonEdit.Utils;

namespace ICSharpCode.AvalonEdit.Editing
{
    sealed class CaretLayer : Layer
    {
        TextArea textArea;

        bool isVisible;
        Rect caretRectangle;

        DispatcherTimer caretBlinkTimer = new DispatcherTimer();
        bool blink;

        public CaretLayer(TextArea textArea) : base(textArea.TextView, KnownLayer.Caret)
        {
            this.textArea = textArea;
            this.IsHitTestVisible = false;
            caretBlinkTimer.Tick += new EventHandler(caretBlinkTimer_Tick);
        }

        void caretBlinkTimer_Tick(object sender, EventArgs e)
        {
            blink = !blink;
            InvalidateVisual();
        }

        public void Show(Rect caretRectangle)
        {
            this.caretRectangle = caretRectangle;
            this.isVisible = true;
            StartBlinkAnimation();
            InvalidateVisual();
        }

        public void Hide()
        {
            if (isVisible)
            {
                isVisible = false;
                StopBlinkAnimation();
                InvalidateVisual();
            }
        }
        
        void StartBlinkAnimation()
        {
            TimeSpan blinkTime = Win32.CaretBlinkTime;
            blink = true; // the caret should visible initially
                          // This is important if blinking is disabled (system reports a negative blinkTime)
            if (blinkTime.TotalMilliseconds > 0)
            {
                caretBlinkTimer.Interval = blinkTime;
                caretBlinkTimer.Start();
            }
        }

        void StopBlinkAnimation()
        {
            caretBlinkTimer.Stop();
        }

        internal Brush CaretBrush;

        protected override void OnRender(DrawingContext drawingContext)
        {
            base.OnRender(drawingContext);
            if (isVisible && blink)
            {
                Brush caretBrush = this.CaretBrush;
                if (caretBrush == null)
                    caretBrush = (Brush)textView.GetValue(TextBlock.ForegroundProperty);

                if (this.textArea.OverstrikeMode || this.textArea.MovingMode)
                {
                    SolidColorBrush scBrush = caretBrush as SolidColorBrush;
                    if (scBrush != null)
                    {
                        Color brushColor = scBrush.Color;
                        Color newColor = Color.FromArgb(100, brushColor.R, brushColor.G, brushColor.B);
                        caretBrush = new SolidColorBrush(newColor);
                        caretBrush.Freeze();
                    }
                }

                Rect r = new Rect(caretRectangle.X - textView.HorizontalOffset,
                                  caretRectangle.Y - textView.VerticalOffset,
                                  caretRectangle.Width,
                                  caretRectangle.Height);
                drawingContext.DrawRectangle(caretBrush, null, PixelSnapHelpers.Round(r, PixelSnapHelpers.GetPixelSize(this)));
            }
        }
    }
}
